1. Field of the Invention
This invention is concerned with paints and lacquers and relates to new oxidatively curing binders and to their use.
2. Discussion of Related Art
Paints are basically divided into physically drying systems and chemically drying systems. In the first case, the paint film is formed from the paint binders (film formers, resins, plasticizers) dissolved or dispersed in the solvent by evaporation of the solvent with no further chemical reaction. In the second case, application of the paint to the surface is followed by a chemical reaction which leads to crosslinking in the paint film, with the result that there is a drastic reduction in the redissolvability of the dried (cured) film compared with the original paint constituents.
One form of chemically drying paints are the oxidatively drying systems in which the crosslinking reaction is initiated by atmospheric oxygen. Oxidatively drying systems include the old oil paints and oil lacquers which contained highly unsaturated oils, such as linseed oil and soybean oil (so-called drying oils), together with siccatives (drying aids) as oxidatively crosslinking binders. However, their drying time is too long for present-day requirements. Presently the most important oxidatively curing paints are based on alkyd resins in which highly unsaturated fatty acids in the form of mixed polyesters are incorporated by condensation. To guarantee adequate quality of the paint film, the characteristic data of the alkyd precondensates which are incorporated in the paints have to be kept very constant. Naturally this involves very considerable care and effort so far as the conduct of the condensation reaction is concerned. In addition, the presence of the ester bond means that the alkyd resins remain somewhat vulnerable to hydrolysis.
The problem addressed by the present invention in this regard was to find other alternatives and to develop more suitable systems.
It has been found that this problem can be solved by addition of certain poly-N-acylalkyleneimines to the paints.